Low profile electrodes for a shock wave catheter

ABSTRACT

The invention provides a device for generating shock waves. The device may comprise an elongated tube and a conductive sheath circumferentially mounted around the elongated tube. The device may further comprise first and second insulated wires extending along the outer surface of the elongated tube. A portion of the first insulated wire is removed to form a first inner electrode, which is adjacent to a first side edge of the conductive sheath. A portion of the second insulated wire is removed to form a second inner electrode, which is adjacent to a second side edge of the conductive sheath. Responsive to a high voltage being applied across the first inner electrode and the second inner electrode, a first shock wave is created across the first side edge and the first inner electrode, and a second shock wave is created across the second side edge and the second inner electrode.

The present disclosure relates generally to shock wave electrodes, andmore specifically, to electrodes for the generation of shock waveswithin vascular structures.

BACKGROUND

The present invention relates to a treatment system for percutaneouscoronary angioplasty or peripheral angioplasty in which an angioplastyballoon is used to dilate a lesion (e.g., calcified lesion) and restorenormal blood flow in the artery. In this type of procedure, a cathetercarrying a balloon is advanced into the vasculature along a guide wireuntil the balloon is aligned with calcified plaques. The balloon is thenpressurized to reduce or break the calcified plaques and push them backinto the vessel wall.

More recently, the assignee herein has developed a treatment system thatincludes electrodes within an angioplasty type balloon. In use, theballoon is advanced to the region of an occlusion. The balloon is thenpartially pressurized with a conductive fluid. A series of high voltagepulses are applied to the electrodes within the balloon, with each pulsegenerating a shock wave in the conductive fluid. The shock waves passthrough the balloon wall and into the occlusion, cracking the calcifiedplaques. Once the calcified plaques are cracked, the balloon can befurther expanded to open the vessel. Such system is disclosed in U.S.Pat. Nos. 8,956,371 and 8,888,788, both of which are incorporated hereinby reference. Further, the assignee herein has developed techniques forproviding an electrode on the tip of a guide wire for generating forwarddirected shock waves. This approach is disclosed in U.S. PatentPublication No. 2015/0320432, also incorporated herein by reference.

The present invention relates to yet another alternative for placingshock wave electrodes near an occlusion. This approach can be used alongor in conjunction with an angioplasty balloon.

BRIEF SUMMARY

The invention provides a device for generating shock waves. In someembodiments, the device comprises an elongated tube and a conductivesheath circumferentially mounted around the elongated tube. The devicefurther comprises a first insulated wire extending along the outersurface of the elongated tube and a second insulated wire extendingalong the outer surface of the elongated tube. A portion of the firstinsulated wire is removed to form a first inner electrode and the firstinner electrode is adjacent to a first side edge of the conductivesheath. A portion of the second insulated wire is removed to form asecond inner electrode and the second inner electrode is adjacent to asecond side edge of the conductive sheath. When a high voltage isapplied across the first inner electrode and the second inner electrode,a current is configured to flow from the first wire to the first sideedge of the conductive sheath and from the second side edge of theconductive sheath to the second wire. A first shock wave is createdacross the first side edge of the conductive sheath and the first innerelectrode, and a second shock wave is created across the second sideedge of the conductive sheath and the second inner electrode.

In some embodiments, the device comprises an elongated tube and threeconductive sheaths each circumferentially mounted around the elongatedtube. The device further comprises a first insulated wire, a secondinsulated wire, a third insulated wire, and an insulated common groundwire, each extending along the outer surface of the elongated tube. Aportion of the first insulated wire is removed to form a first innerelectrode; two portions of the second insulated wire are removed to forma second inner electrode and a third inner electrode; two portions ofthe third insulated wire are removed to form a fourth inner electrodeand a fifth inner electrode; a portion of the insulated common groundwire is removed to form a sixth inner electrode. When a high voltage isapplied across the first wire and the insulated common ground wire, acurrent is configured to flow from the first wire to a first side edgeof the first conductive sheath, from a second side edge of the firstconductive sheath to the second wire, from the second wire to a firstside edge of the second conductive sheath, from a second side edge ofthe second conductive sheath to the third wire, from the third wire to afirst side edge of the third conductive sheath, from a second side edgeof the third conductive sheath to the insulated common ground wire.Accordingly, a first shock wave is created across the first side edge ofthe first conductive sheath and the first inner electrode, a secondshock wave is created across the second side edge of the firstconductive sheath and the second inner electrode, a third shock wave iscreated across the first side edge of the second conductive sheath andthe third inner electrode, a fourth shock wave is created across thesecond side edge of the second conductive sheath and the fourth innerelectrode, a fifth shock wave is created across the first side edge ofthe third conductive sheath and the fifth inner electrode, and a sixthshock wave is created across the second side edge of the thirdconductive sheath and the sixth inner electrode.

In some embodiments, a device for generating shock waves comprises anelongated tube and four conductive sheaths each circumferentiallymounted around the elongated tube. The device further comprises a firstinsulated wire, a second insulated wire, a third insulated wire, afourth insulated wire, and an insulated common ground wire, eachextending along the outer surface of the elongated tube. A portion ofthe first insulated wire is removed to form a first inner electrode; twoportions of the second insulated wire are removed to form a second innerelectrode and a third inner electrode; a portion of the third insulatedwire is removed to form a fifth inner electrode; two portions of thefourth insulated wire are removed to form a sixth inner electrode and aseventh inner electrode; two portions of the insulated common groundwire are removed to form a fourth inner electrode and an eighth innerelectrode. When a high voltage is applied across the first wire and theinsulated common ground wire, a first current is configured to flow fromthe first wire to a first side edge of the first conductive sheath togenerate a first shock wave across the first side edge of the firstconductive sheath and the first inner electrode, from a second side edgeof the first conductive sheath to the second wire to generate a secondshock wave across the second side edge of the first conductive sheathand the second inner electrode, from the second wire to a first sideedge of the second conductive sheath to generate a third shock waveacross the first side edge of the second conductive sheath and the thirdinner electrode, from a second side edge of the second conductive sheathto the insulated common ground wire to generate a fourth shock waveacross the second side edge of the second conductive sheath and thefourth inner electrode. When a high voltage is applied across the thirdwire and the insulated common ground wire, a second current isconfigured to flow from the third insulated wire to a first side edge ofthe third conductive sheath to generate a fifth shock wave across thefirst side edge of the third conductive sheath and the fifth innerelectrode, from a second side edge of the third conductive sheath to thefourth insulated wire to generate a sixth shock wave across the secondside edge of the third conductive sheath and the sixth inner electrode,from the fourth insulated wire to a first side edge of the fourthconductive sheath to generate a seventh shock wave across the first sideedge of the fourth conductive sheath and the seventh inner electrode,and from a second side edge of the fourth conductive sheath to theinsulated common ground wire to generate an eighth shock wave across thesecond side edge of the fourth conductive sheath and the eighth innerelectrode.

DESCRIPTION OF THE FIGURES

FIG. 1 depicts an exemplary shock wave angioplasty device having aplurality of electrode assemblies, in accordance with some embodiments.

FIG. 2A depicts a set of shock wave electrode assemblies in an exemplaryshock wave angioplasty device that may be activated to generate shockwaves at 4 locations, in accordance with some embodiments.

FIG. 2B depicts the connectivity between a plurality of inner electrodesand sheaths to attain the configuration of FIG. 2A, in accordance withsome embodiments.

FIG. 2C depicts an exemplary electrode assembly, in accordance with someembodiments.

FIG. 2D depicts an exemplary electrode assembly, in accordance with someembodiments.

FIG. 2E schematically depicts an electrical diagram of the configurationof FIG. 2A, in accordance with some embodiments.

FIG. 3A depicts a set of shock wave electrode assemblies in an exemplaryshock wave angioplasty device that may be activated to generate shockwaves at 6 locations, in accordance with some embodiments.

FIG. 3B depicts the connectivity between a plurality of inner electrodesand sheaths to attain the configuration of FIG. 3A, in accordance withsome embodiments.

FIG. 4A depicts a set of shock wave electrode assemblies in an exemplaryshock wave angioplasty device that may be activated to generate shockwaves at 8 locations, in accordance with some embodiments.

FIG. 4B depicts the connectivity between a plurality of inner electrodesand sheaths to attain the configuration of FIG. 4A, in accordance withsome embodiments.

FIG. 4C schematically depicts an electrical diagram of the configurationof FIG. 4A, in accordance with some embodiments.

FIG. 4D schematically depicts an electrical diagram of the configurationof FIG. 4A, in accordance with some embodiments.

FIG. 5 depicts a set of shock wave electrode assemblies in an exemplaryshock wave angioplasty device that may be activated to generate shockwaves at 10 locations, in accordance with some embodiments.

FIG. 6A depicts an exemplary sheath that may be used in an electrodeassembly, in accordance with some embodiments.

FIG. 6B depicts an exemplary sheath that may be used in an electrodeassembly, in accordance with some embodiments.

FIG. 6C depicts an exemplary sheath that may be used in an electrodeassembly, in accordance with some embodiments.

FIG. 6D depicts an exemplary sheath that may be used in an electrodeassembly, in accordance with some embodiments.

FIG. 7A depicts an exemplary construction of an electrode assembly, inaccordance with some embodiments.

FIG. 7B depicts an exemplary construction of an electrode assembly, inaccordance with some embodiments.

FIG. 7C depicts an exemplary construction of an electrode assembly, inaccordance with some embodiments.

DETAILED DESCRIPTION

The following description is presented to enable a person of ordinaryskill in the art to make and use the various embodiments. Descriptionsof specific devices, techniques, and applications are provided only asexamples. Various modifications to the examples described herein will bereadily apparent to those of ordinary skill in the art, and the generalprinciples defined herein may be applied to other examples andapplications without departing from the spirit and scope of the variousembodiments. Thus, the various embodiments are not intended to belimited to the examples described herein and shown, but are to beaccorded the scope consistent with the claims.

The assignee herein has developed a number of low-profile shock waveelectrodes that may be suitable for use in angioplasty and/orvalvuloplasty procedures. For example, in U.S. Pat. No. 8,888,788, theassignee discloses a low-profile electrode assembly comprising an innerelectrode, an insulating layer overlaying the inner electrode, and anouter electrode. The outer electrode may be a conductive sheath having acentral opening that is coaxially aligned with an opening in theinsulating layer. In operation, plasma arcs can be formed across theinner electrode and the opening in the outer electrode to generate shockwaves. The above-described design reduces the crossing-profile of theshock wave device because the inner electrode, the outer electrode, andthe insulating layer are stacked, thus allowing the shock wave device toeasily navigate through, access, and treat target vascular tissues.

In operation, the plasma arcs generated across the inner electrode andthe outer electrode cause erosion in the conductive sheath, resulting inwidening of the opening in both directions. As the opening widens, itbecomes more difficult to control the generation, location, and/ormagnitude of plasma arcs (and therefore shock waves), thus negativelyimpacting the longevity of the electrode assembly.

Described herein are shock wave electrode assemblies that are designedto be low-profile and durable. In some embodiments, an outer electrodeis formed by a conductive sheath without an opening on the outersurface, and an inner electrode is formed by removing a portion of aninsulated wire (e.g., cutting a hole in the insulating layer near theend of the wire) to expose an electrically conductive portion of theinsulated wire. The inner electrode is placed a controlled distanceapart from the side edge of the conductive sheath to allow for areproducible arc for a given current and voltage. In operation, plasmaarcs may be formed across the inner electrode and the side edge of theconductive sheath, rather than across the inner electrode and an openingof the sheath. As such, the plasma arcs would cause erosion only in theone direction into the side edge, rather than causing erosion in bothdirections to widen the opening in the previous designs. Thus, thelongevity of the electrode assembly is effectively doubled.Additionally, the present design eliminates the use of an insulatedlayer stacked between the inner electrode and the outer electrode, thusfurther reducing the crossing-profile of the device. In someembodiments, the inner electrode is formed by cutting the end of theinsulated wire to expose an electrically conductive cross-section of thewire, and the end of the insulated wire is placed a controlled distancefrom the side edge of the conductive sheath as described above to formthe electrode assembly. The assembling process is significantly easierthan stacking the electrodes and aligning the opening of the conductivesheath with the opening of the insulating layer as required by previousdesigns, thus reducing manufacture cost and improving the usability andeffectiveness of the shock wave device.

FIG. 1 depicts an exemplary shock wave angioplasty device 100 accordingto an embodiment of the invention. The shock wave device 100 includes anelongated tube 104 and an angioplasty balloon 102. The angioplastyballoon wraps circumferentially around a portion of the elongated tube104 in a sealed configuration via, for example, a seal 122. Theangioplasty balloon 102 forms an annular channel 124 around theelongated tube 104 through which a conductive fluid, such as saline, maybe admitted into the balloon via fill ports 126. The balloon is filledwith the fluid such that the balloon can be inflated and gently fixed tothe walls of the artery in direct proximity with a calcified lesion. Insome embodiments, the fluid may also contain an x-ray contrast to permitfluoroscopic viewing of the catheter during use.

The elongated tube 104 includes a number of longitudinal grooves orchannels configured for retaining wires and/or inner electrodes. In thedepicted example in FIG. 1, the elongated tube 104 has four groovesalong the length of the elongated tube. Insulated wires 130, 132, 134,and 136 are placed within the grooves of the elongated tube 104.Furthermore, a number of conductive sheaths 112, 114, and 116 arecircumferentially mounted around the elongated tube 104. A variable highvoltage pulse generator 150 is connected to the insulated wire 130 andthe insulated wire 136. The insulated wires and the sheaths form threeelectrode assemblies that can be activated to generate shock waves at 6locations (e.g., along the length of the vessel), as discussed in detailbelow. The elongated tube 104 also includes a lumen through which aguide wire 120 is inserted.

In operation, a physician uses the guidewire 120 to guide the elongatedtube 104 into position. Once positioned, the variable high voltage pulsegenerator 150 is used to deliver a series of pulses to create a seriesof shock waves within the angioplasty balloon 102 and within the arterybeing treated. The magnitude of the shock waves can be controlled bycontrolling the magnitude of the pulsed voltage, the current, theduration, and the repetition rate. The physician may start with lowenergy shock waves and increase the energy as needed to crack thecalcified plaques. Such shock waves will be conducted through the fluid,through the balloon, through the blood and vessel wall to the calcifiedlesion where the energy will break the hardened plaque.

FIG. 2A depicts a plurality of shock wave electrode assemblies that maybe included in an exemplary shock wave angioplasty device such as thedevice depicted in FIG. 1. As depicted, the shock wave angioplastydevice 200 includes an elongated tube 204 having four longitudinalgrooves 260, 262, 264, and 268. A number of insulated wires 230, 232,and 236 are disposed on the outer surface of the elongated tube 204 suchthat they extend along the length of the elongated tube. As depicted,the insulated wire 230 is disposed in the groove 264 and the insulatedwire 232 is disposed in the groove 260. The insulated wire 236 has afirst straight portion disposed in the groove 262, a second straightportion disposed in the groove 264, and a curved portion disposedbetween the grooves 262 and 264.

The shock wave angioplasty device 200 further includes a firstconductive sheath 212 and a second conductive sheath 214 eachcircumferentially mounted around the elongated tube 204. As depicted inFIGS. 2A and 2B, the length of the first conductive sheath 212 overlapswith and covers a portion of the insulated wire 230 near its distal end,a portion of the insulated wire 232 near its proximal end, and a portionof the insulated wire 236. The length of the second conductive sheath214 overlaps with and covers a portion of the insulated wire 232 nearits distal end and a portion of the insulated wire 236 near its distalend.

The electrode assemblies of the shock wave angioplasty device 200 aredescribed below with reference to FIGS. 2C and 2D. Turning to FIG. 2C, aportion of the insulating layer of the wire 230 is removed near thedistal end of the wire 230 to expose an electrically conductive wireportion, forming the first inner electrode 230 a. In the depictedexample, a hole in the insulating layer is cut on the curved outersurface along the length of the wire. The removed portion may be in anyshape, such as a circle, a rectangle, a strip around the circumferenceof the wire, etc. The location, shape, and size of the removed portionmay vary to control the location, direction, and/or magnitude of theshock wave. In some embodiments, an inner electrode may be formed bycutting the end of the wire to expose an electrically conductivecross-section of the wire. In some embodiments, flat wires rather thanround wires are used to further reduce the crossing profile of theelectrode assembly.

As shown in FIG. 2C, the first inner electrode 230 a is adjacent to, butnot in contact with, a distal side edge 213 of the first conductivesheath 212. The first conductive sheath 212 functions as an outerelectrode, and the first inner electrode 230 a is placed a controlleddistance apart from the distal side edge 213 of the first conductivesheath to allow for a reproducible arc for a given voltage and current.The electrical arcs are then used to generate shock waves in theconductive fluid. In operation, a first shock wave is created across thefirst inner electrode 230 a and the distal side edge 213 of the firstconductive sheath 212, the details of which are provided below withreference to FIG. 2E.

In a similar manner, a portion of the insulated wire 232 is removed toform a second inner electrode 232 a. Specifically, a portion of theinsulating layer of the wire 232 is removed near the proximal end of thewire 232 to expose an electrically conductive wire portion along thelength of the wire, forming the second inner electrode 232 a. As shown,the second inner electrode 232 a is adjacent to, but not in contactwith, a proximal side edge 211 of the first conductive sheath 212.Further, the first inner electrode 230 a and the second inner electrode232 a are positioned circumferentially 180 degrees from each other. Inoperation, the first conductive sheath 212 acts as an outer electrodeand a second shock wave is created across the second inner electrode 232a and the proximal side edge 211 of the first conductive sheath 212, thedetails of which are provided below with reference to FIG. 2E.

Turning to FIG. 2D, a third inner electrode 232 b is formed on theinsulated wire 232 and a fourth inner electrode 236 a is formed on theinsulated wire 236 in a similar manner as described above with referenceto FIG. 2C. As depicted, the third inner electrode 232 b is formed nearthe distal end of the insulated wire 232 and is adjacent to, but not incontact with, a distal side edge 215 of the second conductive sheath214. The fourth inner electrode 236 a is formed near the distal end ofthe insulated wire 236 and is adjacent to, but not in contact with, thesame distal side edge 215 of the second conductive sheath 214. Inoperation, the second conductive sheath 214 acts as an outer electrode,a third shock wave is created across the third electrode 232 b and thedistal side edge 215 and a fourth shock wave is created across thefourth electrode 236 a and the distal side edge 215, the details ofwhich are provided below with reference to FIG. 2E.

In the depicted example in FIGS. 2C and 2D, the first conductive sheath212 includes a first arcuate cut-out on the distal side edge 213, andthe first inner electrode 230 a is positioned adjacent to the firstarcuate cut-out such that the first shock wave is created across thefirst arcuate cut-out and the first inner electrode. Further, the firstconductive sheath 212 includes a second arcuate cut-out on the proximalside edge 211 positioned circumferentially 180 degrees from the firstcut-out, and the second inner electrode 232 a is positioned adjacent tothe second arcuate cut-out such that the second shock wave is createdacross the second arcuate cut-out and the second inner electrode. Thecut-outs on the conductive sheath allow the inner electrodes to beplaced closer to the sheath without coming into direct contact with thesheath, and also allows for better control of the locations of the shockwaves and more predictable and even wear on the conductive sheath. Itshould be appreciated by one of ordinary skill in the art that a shockwave can be generated between an inner electrode and a straight sideedge of the conductive sheath that does not include any cut-outs.

FIG. 2E schematically depicts an electrical diagram of the configurationof FIGS. 2A-D, in accordance with some embodiments. When a high voltageis applied (e.g., using the high voltage pulse generator 150 of FIG. 1)across the proximal end of the insulated wire 230 and the proximal endof the insulated wire 236, a current may flow as indicated by thearrows, with the insulated wire 236 as the common ground wire (i.e.,connecting to a ground or negative channel). As shown, the current flowsfrom the proximal end of the insulated wire 230 toward to the distal endof the insulated wire 230 and, via the insulation removed spot that iselectrically conductive (i.e., the first inner electrode 230 a), to thedistal side edge 213 of the first conductive sheath 212 (i.e., the firstouter electrode). The duration and the magnitude of the voltage pulseare set to be sufficient to generate a gas bubble at the surface of thefirst inner electrode 230 a causing a plasma arc of electric current totraverse the bubble and create a rapidly expanding and collapsingbubble, which creates the mechanical shock wave in the balloon. The sizeof the bubble and the rate of expansion and collapse of the bubble (andtherefore the magnitude, duration, and distribution of the mechanicalforce) may vary based on the magnitude and duration of the voltagepulse, as well as the distance between the inner and outer electrodes,the surface area of the electrodes, and/or the shape of the outerelectrode (e.g., whether there is an arcuate cut-out on the side edge).

The current may further traverse from the proximal side edge 211 of thefirst conductive sheath 212 (i.e., the first outer electrode) to theinsulated wire 232, via the insulation removed spot near the proximalend of the insulated wire 232 (i.e., the second inner electrode 232 a).The voltage pulse may create a potential difference between the firstouter electrode and the second inner electrode high enough to form aplasma arc between them, generating a bubble that gives rise to a secondshock wave. In the depicted example, the first inner electrode 230 a andthe second inner electrode 232 a are located circumferentially oppositeto each other (e.g., 180 degrees apart around the circumference of theelongated tube), and thus the first shock wave and the second shock wavemay propagate in opposite directions, extending outward from the side ofthe elongated tube.

The current may further traverse from the proximal end of the insulatedwire 232 toward to the distal end of the wire and, via the insulationremoved spot that is electrically conductive near the distal end of thewire (i.e., the third inner electrode 232 b), to the distal side edge215 of the second conductive sheath 214 (i.e., the second outerelectrode). The high voltage pulse generator may apply a voltage pulsesuch that the potential difference between the third inner electrode 232b and the second outer electrode is high enough to form a plasma arcbetween them, generating a bubble that gives rise to a third shock wave.

The current may further traverse from the distal side edge 215 of thesecond conductive sheath 214 to the insulated wire 236, via theinsulation removed spot on the insulated wire 236 (i.e., the fourthinner electrode 236 a). The voltage pulse may create a potentialdifference between the second outer electrode and the fourth innerelectrode high enough to form a plasma arc between them, generating abubble that gives rise to a fourth shock wave. The current then returnsto the voltage source generator via the insulated wire 236 to a voltageoutput port (not depicted), which may be a negative channel or a groundchannel. Optionally, a connector (not depicted) may be provided betweenthe insulated wires 230 and 236 and the voltage pulse generator so thatthe wires may be easily connected to the output ports of the highvoltage generator. It should be appreciated that the configurationdepicted in FIG. 2E can operate as described above regardless of whetherthe side edges of the conductive sheaths are straight or have arcuatecut-outs.

In the embodiments depicted in FIGS. 2A-E, each electrode assemblyincludes a pair of inner electrodes configured to generate shock wavesat two locations. For example, the electrode assembly consisting ofconductive sheath 212 and inner electrodes 230 a and 232 a is configuredto generate two shock waves via the two inner electrodes positionedcircumferentially 180 degrees from each other. Further, the device 200includes multiple electrode assemblies along the length of the elongatedtube. Since the magnitude, duration, and distribution of the mechanicalforce impinging on a portion of tissue depends at least in part on thelocation and distance between the shock wave source and the tissueportion, a shock wave device having multiple shock wave electrodes atdifferent locations (circumferentially and longitudinally) may help toprovide consistent or uniform mechanical force to a region of tissue.The plurality of electrodes may be distributed across the device tominimize the distance between the shock wave source(s) and the tissuelocation being treated. In some embodiments, the elongated tube may besized and shaped to distribute shock wave forces to a non-linearanatomical region (e.g., valve and/or valve leaflets). It should also beappreciated that the voltage polarity can be reversed and current flowin the opposite direction.

It should be appreciated that, in some embodiments, an electrodeassembly may include a single inner electrode that is configured togenerate shock wave at a single location. For example, with reference toFIG. 2E, insulated wires 232 and 236 may be removed, and a common groundwire may connect the conductive sheath 322 (e.g., the distal edge 213 ofthe conductive sheath) directly to the ground or negative channel of avoltage source. This way, as a current flows from the insulated wire 230to the conductive sheath 212 to the common ground wire, a shock wave isgenerated at a single location (i.e., across the inner electrode 230 aand the distal side edge 213 of the conductive sheath).

FIGS. 3A-3B depict another set of shock wave electrode assemblies thatmay be included in an exemplary shock wave angioplasty device such asthe device depicted in FIG. 1. As discussed above, FIGS. 2A-2E relate toan exemplary configuration of electrode assemblies that may be activatedto generate shock waves at 4 locations. In contrast, FIGS. 3A-3B relateto an exemplary configuration of electrode assemblies that may beactivated to generate shock waves at 6 locations, as discussed below.

As depicted in FIG. 3A, an exemplary shock wave angioplasty device 300comprises an elongated tube 304 having four longitudinal grooves on theouter surface. A first conductive sheath 312, a second conductive sheath314, and a third conductive sheath 316 are each circumferentiallymounted around the elongated tube 304. A number of insulated wires 330,332, 334, and 336 are disposed on the outer surface of the elongatedtube 304 such that they extend along the outer surface of the elongatedtube. In particular, the insulated wire 330 is disposed within a singlegroove in its entirety, while the insulated wires 332, 334, and 336 areeach disposed within multiple grooves. For example, as shown in FIG. 3A,the insulated wire 334 includes a first straight portion disposed withinone groove, a second straight portion disposed within the adjacentgroove, and a curved portion disclosed between the two grooves.

The conductive sheaths 312, 314, and 316 and the insulated wires 330,332, 334, and 336 form three electrode assemblies that can be activatedto generate shock waves at 6 locations. Turning to FIG. 3B, a portion ofthe insulated wire 330 is removed to form a first inner electrode 330 a.As discussed above, a portion of the insulating layer of the wire 330may be removed by cutting a hole in the insulating layer near the distalend of the wire 330 to expose an electrically conductive wire portionalong the length of the wire, forming the first inner electrode 330 a.Alternatively, the inner electrode 330 a may be formed by cutting thedistal end of the wire to expose an electrically conductivecross-section of the wire. As shown, the first inner electrode 330 a isadjacent to, but not in contact with, the distal side edge of the firstconductive sheath 312. In operation, the first conductive sheath 312acts as an outer electrode and a first shock wave is created across thefirst inner electrode 330 a and the distal side edge of the firstconductive sheath 312.

Furthermore, a second inner electrode 332 a and a third inner electrode332 b are formed by removing a portion of the insulated wire 332 (e.g.,cutting a hole in the insulating layer, cutting the end of the wire toexpose an electrically conductive cross section) near the proximal endand removing a portion of the insulated wire 332 near the distal end,respectively. A fourth inner electrode 334 a and a fifth inner electrode334 b are formed by removing a portion of the insulated wire 334 nearthe proximal end and removing a portion of the insulated wire 334 nearthe distal end, respectively. A sixth inner electrode 336 a is formed byremoving a portion of the insulated wire 336 near the distal end.

In operation, the proximal end of the insulated wire 330 and theproximal end of the insulated wire 336 are connected to the output portsof a high voltage pulse generator (e.g., the high voltage pulsegenerator 150 in FIG. 1). A high voltage is applied across the insulatedwire 330 and 336 such that a current flows as indicated by the arrows inFIG. 3B, with the insulated wire 336 as the common ground wire.Specifically, the current traverses from the insulated wire 330 to thedistal side edge of the first conductive sheath 312, creating a firstshock wave across the first inner electrode 330 a and the distal sideedge. The current then traverses from the proximal side edge of thefirst conductive sheath 312 to the insulated wire 332, creating a secondshock wave across the proximal side edge and the second inner electrode332 a. The first inner electrode 330 a and the second inner electrode332 a are positioned circumferentially 180 degrees from each other. Assuch, the first shock wave and the second shock wave may propagate inopposite directions, extending outward from the side of the elongatedtube.

The current then traverses from insulated wire 332 to the distal sideedge of the second conductive sheath 314, creating a third shock waveacross the third inner electrode 332 b and the distal side edge. Thecurrent then traverses from the proximal side edge of the secondconductive sheath 314 to the insulated wire 334, creating a fourth shockwave across the proximal side edge of the second conductive sheath 314and the fourth inner electrode 334 a. The third inner electrode 332 band the fourth inner electrode 334 a are positioned circumferentially180 degrees from each other. Further, the first inner electrode 330 aand the third inner electrode 332 b are positioned circumferentially 90degrees from each other. As depicted in FIG. 3B, the first innerelectrode 330 a is positioned adjacent to an arcuate cut-out 350 on thedistal side edge of the first conductive sheath 312, while the thirdinner electrode 332 b is positioned adjacent to an arcuate cut-out 351on the distal side edge of the second conductive sheath. As depicted,the two cut-outs 350 and 351 are positioned circumferentially 90 degreesfrom each other.

The current then traverses from the insulated wire 334 to the distalside edge of the third conductive sheath 316, creating a fifth shockwave across the distal side edge of the third conductive sheath 316 andthe fifth inner electrode 334 b. The current then traverses from thedistal side edge of the third conductive sheath 316 to the insulatedwire 336, creating a sixth shock wave across the distal side edge of thethird conductive sheath 316 and the sixth inner electrode 336 a. Thecurrent then returns to the output port (not depicted), which may be anegative channel or a ground channel.

In the depicted example in FIG. 3B, the first shock wave and the secondshock wave are generated on the distal side edge and the proximal sideedge of the first conductive sheath 312, respectively, due to thediagonal placement of the inner electrodes 330 a and 332 a relative tothe first conductive sheath 312. The diagonal placement of the innerelectrodes allows the sonic output to be distributed more evenlylongitudinally along the balloon while making the shock waves lessannular. In contrast, the fifth shock wave and the sixth shock wave areboth generated on the distal side edge of the third conductive sheath316, due to the placement of the inner electrodes 334 b and 336 arelative to the third conductive sheath 316. These configurationsmaintain the continuity in case a wire breaks at the firing spot. One ofordinary skill in the art should recognize that the location of a shockwave can be configured in a flexible manner by arranging thecorresponding wire and the corresponding conductive sheath (and thelocation of the corresponding cut-out on the sheath, if available)accordingly.

FIGS. 4A-D depict another set of shock wave electrode assemblies thatmay be included an exemplary shock wave angioplasty device such as thedevice depicted in FIG. 1. As described above, the embodiments depictedin FIGS. 2A-2E and FIGS. 3A-B can each generate shock waves at multiplelocations (4 and 6 respectively) via a single current. In contrast, theembodiment depicted in FIGS. 4A-D relate to an exemplary configurationof electrode assemblies that may be activated to generate multiple shockwaves via multiple currents, as discussed below. Specifically, twoseparate currents are generated in order to create shock waves in eightlocations.

As depicted in FIG. 4A and FIG. 4B, an exemplary shock wave angioplastydevice 400 comprises an elongated tube 404 having four longitudinalgrooves on the outer surface. A first conductive sheath 412, a secondconductive sheath 414, a third conductive sheath 416, and a fourthconductive sheath 418 are each circumferentially mounted around theelongated tube 404. A number of insulated wires 430, 432, 434, 436, and438 are disposed on the outer surface of the elongated tube 404 suchthat they extend along the outer surface of the elongated tube. Inparticular, some insulated wires (e.g., insulated wires 432 and 436) areeach disposed within a single groove in its entirety, while someinsulated wires (e.g., insulated wires 434 and 438) are each disposedwithin multiple grooves.

The conductive sheaths 412, 414, 416, and 418 and the insulated wires430, 432, 434, 436, and 438 form four electrode assemblies that can beactivated to generate shock waves at 8 locations. Turning to FIG. 4B, aportion of the insulated wire 430 is removed to form a first innerelectrode 430 a. Furthermore, a second inner electrode 432 a and a thirdinner electrode 432 b are formed by removing a portion of the insulatedwire 432 near the proximal end and removing a portion of the insulatedwire 432 near the distal end, respectively. A fourth inner electrode 438a is formed by removing a portion of the insulated wire 438. A fifthinner electrode 434 a is formed by removing a portion of the insulatedwire 434 near the distal end. A sixth inner electrode 436 a and aseventh inner electrode 436 b are formed by removing a portion of theinsulated wire 436 near the proximal end and removing a portion of theinsulated wire 436 near the distal end, respectively. An eighth innerelectrode 438 b is formed by removing a portion of the insulated wire438 near the distal end.

Any of inner electrodes 430 a, 432 a, 432 b, 434 a, 434 b, 436 a, 436 b,and 438 b may be formed by removing a portion of the corresponding wirein any manner that can expose an electrically conductive portion of thewire, for example, by cutting a hole in the insulating layer or cuttingthe end of the wire to expose an electrically conductive cross section.Inner electrode 438 a may be formed by removing a portion of theinsulated wire 438 (e.g., cutting a hole in the insulating layer) on theouter surface of the wire adjacent to a side edge of the secondconductive sheath 414.

FIG. 4C schematically depicts an electrical diagram of the configurationof FIGS. 4A and 4B, in accordance with some embodiments. In operation,the proximal end of the insulated wire 430 and the proximal end of theinsulated wire 438 are first connected to the output ports of a highvoltage pulse generator (e.g., the high voltage pulse generator 150 inFIG. 1), with the insulated wire 438 as the common ground wire. A highvoltage is applied across the insulated wire 430 and 438 such that afirst current 4 a flows as indicated by the arrows in FIG. 4C.Specifically, the first current 4 a traverses from the insulated wire430 to the distal side edge of the first conductive sheath 412, creatinga first shock wave across the first inner electrode 430 a and the distalside edge of the first conductive sheath 412. The first current 4 a thentraverses from the proximal side edge of the first conductive sheath 412to the insulated wire 432, creating a second shock wave across theproximal side edge of the first conductive sheath 412 and the secondinner electrode 432 a. The current then traverses from insulated wire432 to the distal side edge of the second conductive sheath 414,creating a third shock wave across the third inner electrode 432 b andthe distal side edge of the second conductive sheath 414. The currentthen traverses from the proximal side edge of the second conductivesheath 414 to the insulated wire 438, creating a fourth shock waveacross the proximal side edge of the second conductive sheath 414 andthe fourth inner electrode 438 a. The current then returns to the outputport (not depicted), which may be a negative channel or a groundchannel.

FIG. 4D schematically depicts another electrical diagram of theconfiguration of FIGS. 4A and 4B, in accordance with some embodiments.The proximal end of the insulated wire 434 and the proximal end of theinsulated wire 438 can be connected to the output ports of the highvoltage pulse generator (e.g., the high voltage pulse generator 150 inFIG. 1). The high voltage is applied across the insulated wire 434 and438 such that a second current 4 b flows as indicated by the arrows inFIG. 4C. Specifically, the first current 4 b traverses from theinsulated wire 434 to the distal side edge of the third conductivesheath 416, creating a fifth shock wave across the fifth inner electrode434 a and the distal side edge of the third conductive sheath 416. Thesecond current 4 b then traverses from the proximal side edge of thethird conductive sheath 416 to the insulated wire 436, creating a sixthshock wave across the proximal side edge of the third conductive sheath416 and the sixth inner electrode 436 a. The current then traverses frominsulated wire 436 to the distal side edge of the fourth conductivesheath 418, creating a seventh shock wave across the seventh innerelectrode 436 b and the distal side edge of the fourth conductive sheath418. The current then traverses from the distal side edge of the fourthconductive sheath 418 to the insulated wire 438, creating a eighth shockwave across the distal side edge of the fourth conductive sheath 418 andthe eighth inner electrode 438 b. The current then returns to the outputport (not depicted), which may be a negative channel or a groundchannel.

As such, in the embodiment shown in FIGS. 4A-D, two voltage channels areused to generate two separate current flows, which in turn generateshock waves at 8 different locations. In some embodiments, the highvoltage pulse generator may drive the insulated wire 430 and 434simultaneously. For example, the physician may simultaneously connectthe insulated wire 430 to a first positive lead of the pulse generator,connect the insulated wire 434 to a second positive lead of the pulsegenerator, and connect the insulated wire 438 to a negative lead or theground. In some embodiments, the high voltage pulse generator may applyvoltage pulses sequentially (e.g., a voltage pulse is applied to theinsulated wire 430 without applying a pulse to the insulated wire 434).In some embodiments, the voltage pulses applied to the insulated wire434 may be delayed with respect to the voltage pulses applied to theinsulated wire 430. In some embodiments, a multiplexor may be used withthe high voltage pulse generator to control application of pulses. Thismay allow shock waves with different frequency, magnitude, and timing tobe generated along the elongated tube. In the depicted embodiment inFIGS. 4A-D, the two voltage channels share the same common ground wire(i.e., insulated wire 438). One of ordinary skill in the art shouldunderstand that any number of voltage channels (e.g., 4) may beconfigured around a single elongated tube, and these voltage channelsmay rely on the same or different common ground wires.

In contrast with the embodiment depicted in FIGS. 3A-B, in which threeelectrode assemblies are connected in series, the embodiment depicted inFIGS. 4A-D is configured such that some of the electrode assemblies(e.g., any electrode assembly on the path of current 4 a vs. anyelectrode assembly on the path of current 4 b) operate on differentvoltage channels. The series configuration (e.g., as shown in FIGS.3A-B) may allow for more shock waves to be simultaneously generatedusing fewer wires than if, for example, each electrode assembly isconnected to a separate voltage channel. Reducing the number of wiresalong the length of the elongated tube may help to maintain the abilityof the elongated tube to bend and flex (e.g., to navigate throughtortuous vasculature) and fit into more treatment areas. On the otherhand, the voltage applied to a series configuration needs to be greaterand/or of longer duration than the voltage applied to electrodeassemblies each connected to separate voltage channels in order toattain a shock wave of similar magnitude. As such, a shock wave asdepicted in FIG. 4A-D, in which some electrode assemblies are connectedin series (e.g., conductive sheaths 412 and 414) while some electrodeassemblies are controlled by different voltage channels (e.g.,conductive sheaths 412 and 416), may provide the ability to apply astronger shock wave when desired, but also have the ability tosimultaneously apply many shock waves without substantially compromisingthe flexibility and turning capability of the device by minimizing thenumber of wires.

It should be appreciated that a shock wave device may include any numberof conductive sheaths and thus, any number of electrode assemblies. FIG.5 depicts another set of shock wave electrode assemblies that may beincluded an exemplary shock wave angioplasty device such as the devicedepicted in FIG. 1. The embodiment depicted in FIG. 5 relates to anexemplary configuration of electrode assemblies that may be activated togenerate 10 shock waves via a single voltage channel. As depicted inFIG. 5, the shock wave device includes five conductive sheaths and sixwires. In operation, in response to a voltage being applied, a currentflows through the six wires as indicated by the arrows, generating tenshockwaves (SW1-SW10) as illustrated.

With reference to FIGS. 1-5, each of the above-described conductivesheaths may be constructed in any electrically conductive material andmay take any shape. As discussed above, any number of cut-outs may becreated on a conductive sheath to improve the performance of theelectrode assembly. In some embodiments, the number and locations of thecut-outs on the conductive sheath may vary based on the intendedconfiguration of the electrode assembly. For example, a conductivesheath depicted in FIG. 6A includes two cut-outs positionedcircumferentially 180 degrees from each other on the same side edge.This embodiment can be used to construct an electrode assembly thatgenerates two shock waves that are circumferentially 180 degrees fromeach other on the same side edge of the conductive sheath, such as theconductive sheaths 214, 316, and 418. As another example, a conductivesheath depicted in FIG. 6B includes two cut-outs positionedcircumferentially 180 degrees from each other on opposite side edges ofthe conductive sheath. This embodiment can be used to construct anelectrode assembly that generates two shock waves that arecircumferentially 180 degrees from each other on the opposite side edgesof the conductive sheath, such as the conductive sheaths 212, 312, and412. In some embodiments, a sheath having a larger number of cut-outsmay be created to improve the versatility of the sheath and reducemanufacture cost. For example, a sheath having four cut-outs that arepositioned circumferentially 90 degrees apart on each side edge of theconductive sheath can be used in place of any of the above-describedconductive sheaths.

Further, a conductive sheath may be created from multiplesub-components. In some embodiments, the conductive sheath includesmultiple sub-components having notches and/or recesses that may beinterlocked to form the conductive sheath, such as the conductive sheathhaving two halves dovetailed together as depicted in FIGS. 6C-D. In someembodiments, the conductive sheath includes multiple sub-components thatcan be pieced together by way of any suitable method, such as soldering,crimping, welding, conductive adhesives, pressure fit, interference fit,to form the conductive sheath. The multiple sub-components may allow foreasy configuration of the electrode assembly because, for example, atechnician may first position the insulated wires into the grooves ofthe elongated tube and then crimp the two halves of the conductivesheath over the elongated tube to amount the conductive sheath.

In some embodiments, the conductive sheath is created as a single pieceto minimize potential damages (e.g., scratching) to the insulated wiresduring assembly. In some embodiments, during assembly, the elongatedtube is stretched to reduce its circumference to allow a conductivesheath to be slid onto the elongated tube. The insulated wires are thenpositioned under the conductive sheath by, for example, sliding thewires into the grooves of the elongated tube. The elongated tube is thenrelaxed such that its circumference is increased and the conductivesheath is securely mounted over the elongated tube.

FIGS. 7A-C depict an exemplary construction of an electrode assembly, inaccordance with some embodiments. As depicted in FIG. 7A, an insulatedwire 630 is positioned on the outer surface of an elongated tube 604,and a conductive sheath 612 is circumferentially mounted on theelongated tube 604 and covers a longitudinal portion of the insulatedwire. Further, a portion of the insulating layer of the wire 630 (alongwith any adhesives applied) is removed from the insulated wire 630 toform an inner electrode 630 a. The inner electrode 630 a (e.g., theinside of the wire) may be made of materials that can withstand highvoltage levels and intense mechanical forces that are generated duringuse, for example, stainless steel, tungsten, nickel, iron, steel, andthe like.

In some embodiments, one or more pieces of tubing (e.g., heat shrinktubing) may be provided over the elongated tube 604 to help retain thewire 630 within the groove while still allowing the wires to slide andmove within the groove(s) to accommodate bending of the elongated tube.For example, one or more bands of shrink tubing may wrapcircumferentially around one or more portions of the insulated wire 630,including one end 613 of the wire 630. In the depicted example in FIG.7B, two bands of heat shrink tubing 640 a and 640 b are used to securethe wire 630, with the bottom band 640 b covering the end 613 of thewire 630 and a portion of the elongated tube 604. In some embodiments,the bottom band 640 b may abut up to the bottom side edge of theconductive sheath 612 while not covering insulation removal spot 630 a.

The generation of plasma arcs may cause the cut-out of the sheath 612 toerode and take on a slot-like shape over time. If the end of the wire631 is cut to form an inner electrode and the end of the wire is notsecured to the elongated tube, the wire may curl up (e.g., like a candlewick) over time, compromising the effectiveness and longevity of theelectrode assembly. By forming the inner electrode using an insulationremoval spot 630 a and securing the end of the wire to the elongatedtube using a shrink tube, the life of the electrode assembly isextended.

Alternatively or additionally, adhesives (e.g., dots of conductiveepoxy) may be applied along a portion of the wire and/or near theconductive sheath to partially secure or retain the wire within thegroove(s) while still maintaining the ability of the wire to partiallymove and shift as the elongated tube bends or curves. In the depictedexample in FIG. 7C, adhesives are applied along the side edges of theconductive sheath 612 and the side edges of the tubing.

In each of the embodiments depicted in FIGS. 2A, 3A, and 4A, theelongated tube includes four longitudinal grooves, spacedcircumferentially 90 degrees apart, for accommodating insulated wires.It should be appreciated that the elongated tube can include any numberof grooves (e.g., 6, 8). For example, for a relatively long balloonhousing a large number of conductive sheaths along the length of theballoon, a larger number of wires may be required. Such system would beeasier to construct, configure, and/or operate using an elongated tubehaving a larger number of grooves.

Any of the shock wave assemblies described herein may be used in anangioplasty procedure for breaking up calcified plaques accumulatedalong the walls of a vessel. One variation of a method may compriseadvancing a guide wire from an entry site on a patient (e.g., an arteryin the groin area of the leg) to the target region of a vessel (e.g., aregion having calcified plaques that need to be broken up). A shock wavedevice comprising an elongated tube with a guide wire lumen, one or moreelectrode assemblies located along the elongated tube, and a balloon maybe advanced over the guide wire to the target region of the vessel. Theshock wave electrode assemblies may be any of the electrode assembliesdescribed herein. The balloon may be collapsed over the elongated memberwhile the device is advanced through the vasculature. The location ofthe shock wave device may be determined by x-ray imaging and/orfluoroscopy. When the shock wave device reaches the target region, theballoon may be inflated by a conductive fluid (e.g., saline and/orsaline mixed with an image contrast agent). The one or more electrodeassemblies may then be activated to generate shock waves to break up thecalcified plaques. The progress of the plaque break-up may be monitoredby x-ray and/or fluoroscopy. The shock wave device may be moved alongthe length of the vessel if the calcified region is longer than thelength of the catheter with the electrode assemblies, and/or if thecalcified region is too far away from the electrode assemblies toreceive the full force of the generated shock waves. For example, theshock wave device may be stepped along the length of a calcified vesselregion to sequentially break up the plaque. The electrode assemblies ofthe shock wave device may be connected in series and/or may be connectedsuch that some electrode assemblies are connected to separate highvoltage channels, which may be activated simultaneously and/orsequentially, as described above. Once the calcified region has beensufficiently treated, the balloon may be inflated further or deflated,and the shock wave device and guide wire may be withdrawn from thepatient.

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications, alterationsand combinations can be made by those skilled in the art withoutdeparting from the scope and spirit of the invention. Any of thevariations of the various shock wave devices disclosed herein caninclude features described by any other shock wave devices orcombination of shock wave devices herein. Furthermore, any of themethods can be used with any of the shock wave devices disclosed.Accordingly, it is not intended that the invention be limited, except asby the appended claims. For all of the variations described above, thesteps of the methods need not be performed sequentially

What is claimed is:
 1. A device for generating shock waves, the devicecomprising: an elongated tube; a conductive sheath circumferentiallymounted around the elongated tube; a flexible member surrounding thesheath, the flexible member being fillable with a conductive fluid; afirst insulated wire extending along the outer surface of the elongatedtube, wherein a portion of the first insulated wire is removed to form afirst inner electrode and wherein the first inner electrode is adjacentto a first end of the conductive sheath; a second insulated wireextending along the outer surface of the elongated tube, wherein aportion of the second insulated wire is removed to form a second innerelectrode and wherein the second inner electrode is adjacent to a secondend of the conductive sheath; wherein, when a high voltage is appliedacross the first inner electrode and the second inner electrode, acurrent is configured to flow from the first wire to the first end ofthe conductive sheath and from the second end of the conductive sheathto the second wire, wherein a first shock wave is created across thefirst end of the conductive sheath and the first inner electrode, andwherein a second shock wave is created across the second end of theconductive sheath and the second inner electrode.
 2. The device of claim1, wherein the first end and the second end are the same end of thesheath.
 3. The device of claim 1, wherein the first end and the secondend are different ends of the sheath.
 4. The device of claim 1, whereinthe elongated tube includes a first groove and a second groove along thelength of the elongated tube, and wherein at least a portion of thefirst wire is disposed within the first groove and at least a portion ofthe second wire is disposed within the second groove.
 5. The device ofclaim 1, further comprising a first piece of tubing wrapping aroundanother portion of the first wire to secure the first wire to theelongated tube, and a second piece of tubing wrapping around anotherportion of the second wire to secure the second wire to the elongatedtube.
 6. The device of claim 1, wherein the first insulated wirecomprises an insulating layer wrapping around the length of the firstinsulated wire, and wherein the distal end of the first wire is exposedfrom the insulating layer to form the first inner electrode.
 7. Thedevice of claim 1, wherein the first insulated wire comprises aninsulating layer wrapping around the first insulated wire, and wherein astrip of the insulating layer is removed to form the first innerelectrode.
 8. The device of claim 1, wherein the first end and thesecond end of the sheath are straight edges.
 9. The device of claim 1,wherein the first end of the conductive sheath comprises a first arcuatecut-out, wherein the second end of the conductive sheath comprises asecond arcuate cut-out, wherein the first shock wave is created acrossthe first arcuate cut-out on the first end of the conductive sheath andthe first inner electrode, and wherein the second shock wave is createdacross the second arcuate cut-out on the second end of the conductivesheath and the second inner electrode.
 10. The device of claim 9,wherein the first arcuate cut-out is positioned circumferentially 180degrees from the second arcuate cut-out.
 11. The device of claim 1,wherein the first shock wave and the second shock wave are initiated inresponse to a voltage being applied to a proximal end of the first wireand a proximal end of the second wire.
 12. The device of claim 1,wherein the conductive sheath is a first conductive sheath, and thedevice further comprising: a second conductive sheath circumferentiallymounted around the elongated tube; an insulated common ground wireextending along the outer surface of the elongated tube, wherein anotherportion of the second insulated wire is removed to form a third innerelectrode adjacent to a first end of the second sheath, wherein aportion of the insulated common ground wire is removed to form a fourthinner electrode adjacent to a second end of the second sheath; wherein,when a high voltage is applied across the first insulated wire and theinsulated common ground wire, a current is configured to flow from thefirst wire to the first end of the first conductive sheath, from thesecond end of the first conductive sheath to the second wire, from thesecond wire to the first end of the second conductive sheath, and fromthe second end of the second conductive sheath to the insulated commonground wire, wherein a third shock wave is created across the first endof the second conductive sheath and the third inner electrode, andwherein a fourth shock wave is created across the second end of thesecond conductive sheath and the fourth inner electrode.
 13. The deviceof claim 12, wherein the common ground wire comprises a first straightportion, a curved portion, and a second straight portion, and whereinthe first straight portion and the second straight portion are placed intwo different grooves of the elongated tube.
 14. The device of claim 1,wherein the flexible member is a balloon.
 15. A device for generatingshock waves, the device comprising: an elongated tube; a firstconductive sheath, a second conductive sheath, and a third conductivesheath, each circumferentially mounted around the elongated tube; afirst insulated wire, a second insulated wire, a third insulated wire,and an insulated common ground wire, each extending along the outersurface of the elongated tube, wherein a portion of the first insulatedwire is removed to form a first inner electrode, wherein two portions ofthe second insulated wire are removed to form a second inner electrodeand a third inner electrode, wherein two portions of the third insulatedwire are removed to form a fourth inner electrode and a fifth innerelectrode, wherein a portion of the insulated common ground wire isremoved to form a sixth inner electrode, wherein when a high voltage isapplied across the first wire and the insulated common ground wire, acurrent is configured to flow: from the first wire to a first end of thefirst conductive sheath, from a second end of the first conductivesheath to the second wire, from the second wire to a end of the secondconductive sheath, from a second end of the second conductive sheath tothe third wire, from the third wire to a end of the third conductivesheath, from a second end of the third conductive sheath to theinsulated common ground wire, wherein a first shock wave is createdacross the first end of the first conductive sheath and the first innerelectrode, wherein a second shock wave is created across the second endof the first conductive sheath and the second inner electrode, wherein athird shock wave is created across the first end of the secondconductive sheath and the third inner electrode, wherein a fourth shockwave is created across the second end of the second conductive sheathand the fourth inner electrode, wherein a fifth shock wave is createdacross the first end of the third conductive sheath and the fifth innerelectrode, wherein a sixth shock wave is created across the second endof the third conductive sheath and the sixth inner electrode.
 16. Thedevice of claim 15, wherein the first end and the second end of thethird conductive sheath are the same end.
 17. The device of claim 15,wherein the first end and the second end of the first conductive sheathare different ends.
 18. The device of claim 15, wherein the second wirecomprises a first straight portion, a curved portion, and a secondstraight portion, and wherein the first straight portion and the secondstraight portion are placed in two different grooves of the elongatedtube.
 19. The device of claim 15, wherein the first shock wave iscreated across an arcuate cut-out on the first end of the firstconductive sheath and the first inner electrode, wherein the third shockwave is created across an arcuate cut-out on the first end of the secondconductive sheath and the third inner electrode, and wherein the arcuatecut-out on the first end of the first conductive sheath is positionedcircumferentially 90 degrees from the arcuate cut-out on the first endof the second conductive sheath.
 20. A device for generating shockwaves, the device comprising: an elongated tube; a first conductivesheath, a second conductive sheath, a third conductive sheath, a fourthconductive sheath, each circumferentially mounted around the elongatedtube; a first insulated wire, a second insulated wire, a third insulatedwire, a fourth insulated wire, and an insulated common ground wire, eachextending along the outer surface of the elongated tube, wherein aportion of the first insulated wire is removed to form a first innerelectrode, wherein two portions of the second insulated wire are removedto form a second inner electrode and a third inner electrode, wherein aportion of the third insulated wire is removed to form a fifth innerelectrode, wherein two portions of the fourth insulated wire are removedto form a sixth inner electrode and a seventh inner electrode, whereintwo portions of the insulated common ground wire are removed to form afourth inner electrode and an eighth inner electrode, wherein, when ahigh voltage is applied across the first wire and the insulated commonground wire, a first current is configured to flow: from the first wireto a first end of the first conductive sheath to generate a first shockwave across the first end of the first conductive sheath and the firstinner electrode, from a second end of the first conductive sheath to thesecond wire to generate a second shock wave across the second end of thefirst conductive sheath and the second inner electrode, from the secondwire to a first end of the second conductive sheath to generate a thirdshock wave across the first end of the second conductive sheath and thethird inner electrode, from a second end of the second conductive sheathto the insulated common ground wire to generate a fourth shock waveacross the second end of the second conductive sheath and the fourthinner electrode, wherein, when a high voltage is applied across thethird wire and the insulated common ground wire, a second current isconfigured to flow: from the third insulated wire to a first end of thethird conductive sheath to generate a fifth shock wave across the firstend of the third conductive sheath and the fifth inner electrode, from asecond end of the third conductive sheath to the fourth insulated wireto generate a sixth shock wave across the second end of the thirdconductive sheath and the sixth inner electrode, from the fourthinsulated wire to a first end of the fourth conductive sheath togenerate a seventh shock wave across the first end of the fourthconductive sheath and the seventh inner electrode, from a second end ofthe fourth conductive sheath to the insulated common ground wire togenerate an eighth shock wave across the second end of the fourthconductive sheath and the eighth inner electrode.
 21. The device ofclaim 20, wherein the first end and the second end of the firstconductive sheath are different ends.
 22. The device of claim 20,wherein the first end and the second end of the fourth conductive sheathare the same end.